1. Medicinal Plants of West Africa;Ayensu,1978
2. The physiological role(s) of secondary (natural) products;Bell,1981
3. The Merck Manual of Diagnosis and Therapy;Berkow,1987
4. General principles of classification and nomenclature in folk biology;Berlin;American Anthropologist,1973
5. Exaptation as an alternative to coevolution in the cardenolide-based chemical defense of monarch butterflies (Danaus Plexippus L.) against avian predators;Brower,1988